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In the year 2000, specimens of Caulerpa taxifolia, a green alga used in tropical aquariums, were found off the coast of California. Native to the Indian Ocean, C. taxifolia is known for aggressive growth and an ability to compete with sea grasses.It is currently on an international list of invasive species. Which of the following best predicts the consequences of the introduction of C. taxifolia to the California coast?

Phytochromes are molecules that change light stimuli into chemical signals, and they are thought to target light-activated genes in plants. A study was conducted to determine how certain cell proteins were made in a plant cell using a phytochrome. Figures 1 and 2 represent findings from the study. In the first part of the diagram, inactive phytochrome P r in the cytoplasm becomes active phytochrome P f r that enters the nucleus in the presence of red light. The next part of the diagram shows that P f r is bound to P I F 3 that is bound to a G Box Promoter and that P f r is also bound to a Transcriptional Complex that is bound to a T A T A box on DNA. A bent arrow above a shaded rectangle to the right of the T A T A box points to the right and is labeled Transcription. An arrow points from the shaded box to a circle labeled M Y B. In the last part of the diagram, the M Y B labeled circle is bound to another Promoter and also contacts a Transcriptional Complex that is bound to a T A T A box on DNA. A bent arrow above a shaded rectangle to the right of the T A T A box points to the right and is labeled Transcription. An arrow points from the shaded box to the label Cell Proteins. Figure 1. Phytochrome response to exposure to red light In the first part of the diagram, active P f r in the cytoplasm becomes inactive P r in the presence of far red light. The next part of the diagram shows an arrow labeled Far Red Light pointing to free P r in the nucleus and away from both P I F 3 bound to a G Box Promoter and a Transcriptional Complex bound to a T A T A box on DNA. A label above a shaded rectangle to the right of the T A T A box reads No Transcription. A second label below the shaded box reads M Y B Type Transcription Factor. The last part of the diagram shows another Promoter and a T A T A box on DNA. Nothing is bound to the promoter, and a Transcriptional Complex is bound to the T A T A box. A label above a shaded rectangle to the right of the T A T A box reads No Transcription. A label below the shaded rectangle reads Other Genes. Figure 2. Phytochrome response to exposure to far‑red light Use the response models shown in Figures 1 and 2 to justify the claim that phytochromes regulate the transcription of genes leading to the production of certain cellular proteins.

The graph below illustrates a logistic growth curve for a population of Euglena. with x-axis labeled time in days from zero to twenty, and y-axis labeled population size in organisms per milliliter. The growth curve starts with a population just above zero at zero days and increases exponentially to three-hundred organisms per milliliter at day ten, then flattening out and remaining at three-hundred. There is a point labeled Q on the curve at day twenty. The population would be most likely to remain at the level shown at Q under which of the following conditions?

Two groups of students attempted to re-create the primitive atmospheric conditions of early Earth using the apparatus represented below. Each group ran the experiment with different gas mixtures in the apparatus. The two apparatuses are the same except for the gases being used. The apparatuses are as follows, from top left clockwise: there is a horizontal pipe with an arrow pointing to the right. The pipe bends down into a round area labeled Gases. There are two wires carrying electric current into the gases, and a label indicating Spark Discharge where the wires enter the round area. From there, a pipe continues down through a condenser, with an arrow pointing straight down next to the pipe. Water Out to the right is indicated at the top of the condenser, and Water In to the left is indicated at the bottom of the condenser. Below the condenser, the pipe continues and there is another arrow pointing straight down. The pipe then curves to the left and bends around a trap, which is labeled Water Containing Organic Compounds. The pipe continues to the left to a round area labeled Boiling Water. The pipe continues up from there, and there is an arrow next to it pointing straight up. There is a branch in the pipe about halfway up the left side of the apparatus, labeled To Vacuum Line, with an arrow pointing to the left. The pipe continues past the branch to where it started. The Gases area in Experiment 1 is labeled: N 2, C H 4, N H 3, H 2 O, and C O 2. The Gases area in Experiment 2 is labeled: S O 2, H 2 S, H 2 O, C H 4, and C O 2. Which of the following statements best justifies the claim that the conditions in at least one of the experiments could generate the molecular building blocks essential for life?

_______ is the enzyme used during replication to attach Okazaki fragments to each other.

Figure 1 shows the changing pattern of human population sizes in rural and urban areas from 1960 to 2016 with regard to the global population. The horizontal axis is labeled Year, and the years 1960 through 2010, in increments of 10, are indicated, as well as the year 2016. The vertical axis is labeled Number of People, and the numbers 0 through 4 billion, in increments of 1 billion, are indicated. The two curves are described as follows. Note that all values are approximate. The curve labeled Urban population, begins at a point with coordinates 1960, comma 1 billion, and curves upwards and to the right at a gradually increasing rate, passing through the point 2000, comma 2.8 billion. The curve ends at the point 2016, comma 4 billion. The curve labeled Rural population, begins above the curve labeled Urban population at the point 1960, comma 2 billion, and moves gradually upwards to the right passing through the point 2000, comma 3.2 billion. The curve then moves gradually upwards and to the right and ends at the point 2016, comma 3.35 billion. The Rural population curve intersects the Urban Population curve at the point 2007, comma 3.25 billion. Figure 1. Comparison of population size in urban and rural areas from 1960 to 2016. A scientist interested in investigating how human population trends might affect local animal species’ richness stipulates a null hypothesis that animal biodiversity in rural areas will be unaffected in the future by the human population trends shown in Figure 1. Which of the following would best refute this null hypothesis?

In the Florida Everglades, Burmese pythons are an invasive species. They were introduced into southern Florida in 1992. These pythons feed on many of the native Florida species, establishing the pythons as the top predator in the environment. By the year 2000, their population had increased dramatically. Figures 1 and 2 display data collected by ecologists studying the results of the Burmese python invasion. Figure 1 shows counts of animals collected from nighttime road surveys in southern Florida, which are used to estimate population size. Figure 2 shows data collected from mosquitoes captured from the wild. DNA sequencing was used to identify the species of blood that the mosquitoes had in their stomachs, identifying various hosts used by the mosquitoes. The categories are labeled along the horizontal axis as follows: White-Tailed Deer, Raccoon, Coyote, Cotton Rat, and Rabbit. Each category has two bars indicated on it, which are each labeled 1996 and 2011 respectively. Each bar has an error range indicated. The vertical axis is labeled Number Observed, per 100 kilometers of road, and the numbers 0 through 3, in increments of 1, are indicated. The data for each bar is presented as follows. Note that all values are approximate. White-Tailed Deer. 1996, 2.7, plus or minus 0.3. 2011, 0.8, plus or minus 0.4. Raccoon. 1996, 1.2, plus or minus 0.2. 2011, 0. 4, plus or minus 0.2. Coyote. 1996, 1.2, plus or minus 0.4. 2011, 0.7, plus or minus 0.3. Cotton Rat. 1996, 0.65, plus or minus 0.2. 2011, 2.5, plus 0.5, minus 0.1. Rabbit. 1996, 1.7, plus or minus 0.3. 2011, 1.3, plus or minus 0.25. Figure 1. Comparison of observations of selected mammals in 1996 and 2011. The horizontal axis is labeled Year, and the years 1979 and 2016 are indicated. The vertical axis is labeled Host Use, in percent total bloodmeals, and the numbers 0 through 90, in increments of 10, are indicated. The 4 line segments are each determined by two points, and are labeled as follows: Cotton Rat, Human, White-tailed deer, and Raccoon. Each line segment is described as follows. Note that all values are approximate. All line segments begin in 1979 and end in 2016. The Cotton Rat line segment is above the Human line segment and crosses the White-tailed deer line segment. The Human line segment crosses the White-tailed deer and Raccoon line segments. The White-tailed deer line segment is above the Raccoon line segment. The line segment labeled Cotton rat begins at the point 1979, comma 15 percent, and moves upwards and to the right to end at the point 2016, comma 80 percent. The line segment labeled Human begins at the point 1979, comma 0 percent, and moves upwards and to the right to end at the point 2016, comma 10 percent. The line segment labeled White-tailed deer begins at the point 1979, comma 30 percent, and moves downwards and to the right to end at the point 2016, comma 2 percent. The line segment labeled Raccoon begins at the point 1979, comma 10 percent, and moves downwards and to the right to end at the point 2016, comma 0 percent. Figure 2. Change in host preference by Culex cedecei between 1979 and 2016. Numbers do not add up to one hundred percent because these represent a subset of all the host species. In 1996, the native Culex cedecei mosquitoes in southern Florida preferentially took blood meals from white-tailed deer and raccoons. It was predicted that changes in host population size would alter these host preferences. Additionally, it is known that cotton rats are often infected by the Everglades virus, which normally exists in animals, but is capable of infecting humans. Ecologists predict that increased feeding on cotton rats by C. cedecei may significantly increase the tendency of this virus to infect humans. Which of the following most accurately explains an impact of Burmese pythons on the Everglades community in southern Florida using the data provided?

Students observed the distribution of different color phenotypes in northern ravine salamanders (Plethodon electromorphus) before and after a spring flood. The data are shown in Table 1. Table 1. Salamander Distribution Before and After a flood Salamander Distribution Before the Flood (n) Salamander Distribution After the Flood (n) Black phenotype 13 7 Dark-brown phenotype 25 14 Light-brown phenotype 6 3 Which of the following is an appropriate null hypothesis regarding the phenotypic frequencies of this population of salamanders before and after the flood?

Ascorbic acid (vitamin C) is an organic molecule necessary for the health of plants and animals. The majority of animals, including most mammals, synthesize ascorbic acid from organic precursors, but some primates are unable to synthesize ascorbic acid and must instead acquire it from dietary sources, such as certain fruits and vegetables. The L-gulonolactone oxidase (GULO) gene encodes an enzyme that catalyzes a required step in the biosynthesis of ascorbic acid. Most mammals carry a functional copy of the GULO gene, but some primates carry only a GULO pseudogene, which is a nonfunctional variant. A comparison of GULO genes and GULO pseudogenes from different animals can provide insight into the evolutionary relatedness of the animals. In Table I, selected members of some mammalian groups are listed, along with an indication of their ability to synthesize ascorbic acid. Table II shows an alignment of amino acid coding sequences from homologous regions of the GULO genes and GULO pseudogenes of the organisms listed in Table I. Figure 1 represents the universal genetic code. The title of the table is SELECTED MAMMALIAN GROUPS. The top row contains the column labels, from left to right: column one, Group; column two, Selected Members; column three, Biosynthesis of Ascorbic Acid. From top to bottom, the data is as follows: Row two: Group, Nonprimate mammals; Selected Members, Elephant, mouse; Biosynthesis of Ascorbic Acid, Yes. Row three: Group, Primate mammals; Selected Members, Lemur; Biosynthesis of Ascorbic Acid, Yes. Row four: Group, Primate mammals; Selected Members, Orangutan, chimpanzee; Biosynthesis of Ascorbic Acid, No. Row five: Group, Primate mammals; Selected Members, Human; Biosynthesis of Ascorbic Acid, No. It lists the relative positions of nucleotides in a non-template (coding) sequence. The table consists of six rows and twenty-seven columns. The row headers are as follows: elephant, mouse, lemur, orangutan, chimp, and human. The column headers run from 5 prime to 3 prime, displaying the positions from 1 (at 5 prime) through 27 (at 3 prime). The row-wise entries from the table are as follows. Row 1, Elephant. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: C (shaded), 6: C (shaded), 7: C, 8: A, 9: T, 10: C (shaded), 11: T (shaded), 12: G (shaded), 13: A, 14: A, 15: G, 16: A (shaded), 17: A (shaded), 18: G (shaded), 19: T, 20: C, 21: G, 22: G (shaded), 23: A (shaded), 24: A (shaded), 25: T, 26: A, 27 (3 prime): C. Row 2, Mouse. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: C, 8: A, 9: C, 10: C (shaded), 11: T (shaded), 12: G (shaded), 13: A, 14: A, 15: G, 16: A (shaded), 17: A (shaded), 18: G (shaded), 19: T, 20: C, 21: T, 22: G (shaded), 23: A (shaded), 24: G (shaded), 25: T, 26: A, 27 (3 prime): C. Row 3, Lemur. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: C, 8: A, 9: C, 10: C (shaded), 11: T (shaded), 12: G (shaded), 13: A, 14: A, 15: G, 16: A (shaded), 17: G (shaded), 18: G (shaded), 19: T, 20: C, 21: C, 22: G (shaded), 23: A (shaded), 24: G (shaded), 25: T, 26: A, 27 (3 prime): C. Row 4, Orangutan. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: en-dash, 8: A, 9: T, 10: T, 11: G (shaded), 12: G (shaded), 13: A (shaded), 14: A, 15: G, 16: A, 17: A (shaded), 18: A (shaded), 19: T (shaded), 20: C, 21: T, 22: G, 23: A (shaded), 24: G (shaded), 25: G (shaded), 26: A, 27 (3 prime): C. Row 5, Chimp. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: en-dash, 8: A, 9: T, 10: T, 11: G (shaded), 12: G (shaded), 13: A (shaded), 14: A, 15: G, 16: A, 17: A (shaded), 18: A (shaded), 19: T (shaded), 20: C, 21: T, 22: G, 23: A (shaded), 24: G (shaded), 25: G (shaded), 26: A, 27 (3 prime): C. Row 6, Human. 1 (5 prime): G, 2: A, 3: C, 4: A (shaded), 5: G (shaded), 6: C (shaded), 7: en-dash, 8: A, 9: T, 10: T, 11: G (shaded), 12: G (shaded), 13: A (shaded), 14: A, 15: G, 16: A, 17: A (shaded), 18: A (shaded), 19: T (shaded), 20: C, 21: T, 22: G, 23: A (shaded), 24: G (shaded), 25: G (shaded), 26: A, 27 (3 prime): C. A footnote below the table reads: For each D N A segment, the alternating shaded and unshaded nucleotides indicate the triplet codons of the open reading frame, shown from left (5 prime) to right (3 prime) as the non-template (coding) strand. An “en-dash” indicates the absence of a nucleotide. The left side of the table is 5 Prime First Base, and labels the main rows, from top to bottom, U, C, A, G. The top side of the table is labeled Second Base, and labels the main columns, from left to right, U, C, A, G. The right side of the table is labeled, 3 Prime Third Base, and labels each of the main rows U C A G. The data in the table reads as follows; First Base U and Second Base U with Third Base U, results in U U U phenylalanine; with Third Base C results in U U C phenylalanine; with Third Base A, results in U U A leucine, and with Third Base G, results in U U G leucine First Base C and Second Base U with Third Base U, results in C U U leucine; with Third Base C, results in C U C leucine; with Third Base A, results in C U A leucine, and with Third Base G, results in C U G leucine First Base A and Second Base U with Third Base U, results in A U U isoleucine; with Third Base C, results in A U C isoleucine; with Third Base A, results in A U A isoleucine; and with Third Base G, results in A U G methionine or start First Base G and Second Base U with Third Base U, results in G U U valine; with Third Base C, results in G U C valine; with Third Base A, results in G U A valine, with Third Base G, results in G U G valine First Base U and Second Base C with Third Base U, results in U C U serine; with Third Base C, results in U C C serine; with Third Base A, results in U C A serine; and with Third Base G, results in U C G serine First Base C and Second Base C with Third Base U, results in C C U proline; with Third Base C, results in C C C proline; with Third Base A, results in C C A proline; and with Third Base G, results in C C G proline First Base A and Second Base C with Third Base U, results in A C U threonine; with Third Base C, results in A C C threonine; with Third Base A, results in A C A threonine; and with Third Base G, results in A C G threonine First Base G and Second Base C with Third Base U, results in G C U alanine; with Third Base C, results in G C C alanine; with Third Base A, results in G C A alanine; and with Third Base G, results in G C G alanine First Base U and Second Base A with Third Base U, results in U A U tyrosine; with Third Base C, results in U A C tyrosine; with Third Base A, results in U A A stop; and with Third Base G, results in U A G stop First Base C and Second Base A with Third Base U, results in C A U histidine; with Third Base C, results in C A C histidine; with Third Base A, results in C A A glutamine; and with Third Base G, results in C A G glutamine First Base A and Second Base A with Third Base U, results in A A U asparagine; with Third Base C, results in A A C asparagine; with Third Base A, results in A A A lysine; and with Third Base G, results in A A G lysine First Base G and Second Base A with Third Base U, results in G A U aspartate; with Third Base C, results in G A C aspartate; with Third Base A, results in G A A glutamate; and with Third Base G, results in G A G glutamate First Base U and Second Base G with Third Base U, results in U G U cysteine; with Third Base C, results in U G C cysteine; with Third Base A, results in U G A stop; and with Third Base G, results in U G G tryptophan First Base C and Second Base G with Third Base U, results in C G U arginine; with Third Base C, results in C G C arginine; with Third Base A, results in C G A arginine; and with Third Base G, results in C G G arginine First Base A and Second Base G with Third Base U, results in A G U serine; with Third Base C, results in A G C serine; with Third Base A, results in A G A arginine; and with Third Base G, results in A G G arginine First Base G and Second Base G with Third Base U, results in G G U glycine; with Third Base C, results in G G C glycine; with Third Base A, results in G G A glycine; and with Third Base G, results in G G G glycine. Comparison of DNA sequences in Table II suggests that a functional GULO gene in lemurs can have a G, C, or T at position 21 but only a G at position 22. Which of the following pairs of predictions is most helpful in explaining the discrepancy?

Scientists want to determine whether the rapid economic growth in China between 1950 and 2000 caused a mass extinction of animal species during that time period. A mass extinction event is considered to occur when the rate of species extinction far exceeds the background extinction rate. The scientists collected data on the number of extinctions of selected vertebrate species in China between 1950 and 2000, as shown in Table 1. Extinction rates were ascertained by measuring the average percent of species lost (PSL). Table 1. The average percent of extinctions of 252 protected vertebrate species in 2,365 counties in China from 1950 to 2000. Mammals Birds Amphibians and Reptiles Background Rate Average PSL ±1 standard deviation 47.4±33.59 19.75±17.70 28.80±28.86 27.21±16.20 Which of the following is the null hypothesis most relevant for evaluating the data in Table 1?